Electrical signalling devices



y 1965 ,1. DOGGART 3,182,307

ELECTRICAL S IGNALLING DEVI CES Filed Feb. 28, 1961 IN l/EN 70B Jb/m/DOGGAET United States Patent O 3,182,307 ELECTRICAL SIGNALLING DEVICESJohn Doggart, Macclesfield, England, assignor to V. 8; E.

Friedland Limited, Macclesfield, England, a British company Filed Feb.28, 1961, Ser. No. 92,226 Claims priority, application Great BritainFeb. 29, 1960 2 Claims. (Cl. 340-492) This invention relates toelectrical signalling devices.

According to one aspect of the invention there is provided for anelectrical signalling device, a coil unit comprising a coil havingprojections at each end thereof and a mounting comprising a base, twospaced resilient arms upstanding from the base and resiliently andreleasably gripping the coil, and a socket in each arm, respectivelyreceiving the projections to locate the coil between the arms. In thisway the coil may be easily and speedily assembled on its mounting whichitself may be arranged for relatively simple assembly in the signallingdevice.

The mounting may be formed from a metal sheet and the two arms may beprovided by spaced portions of the sheet which have been deformed out ofthe plane of the sheet to lie in parallel planes substantiallyperpendicular to the plane of the sheet.

According to another aspect of the invention there is provided for anelectrical signalling device, the combination of a coilunit as set outin either of the preceding paragraphs with a striker and a soundemitting member, preferably a tone bar, which emits a sound on beingstruck by the striker, the sound emitting member being carried by thesaid mounting, and the striker being movable by the coil to strike thesound emitting member.

According to yet a further aspect of the invention there is provided anelectrical signalling device comprising the combination as set out inthe preceding paragraph further comprising a housing encasing the saidcombination and having at least one sound aperture through the wall ofthe casing and aligned with the tone bar, the said combination beinglocated within the housing so that in use the vibrations of the tonebar, or at least its major vibrations, take place in a direction towardsand away from the aperture. Preferably the tone bar is mounted so thatit has at least two antinodes when set into vibration and the casing hastwo apertures aligned, as aforesaid, with the antinodes.

One embodiment of the invention, which is a so-called door-chime willnow be described by way of example with reference to the accompanyingdrawings. In the drawings:

FIGURE 1 is an underplan View, partly in section of a door chimeembodying the invention;

FIGURE 2 is a perspective view of a mounting for the coil unit of thedoor chime of FIGURE 1; and

FIGURE 3 is a side view of the door chime of FIG- URE 1.

Referring now to the drawings, the chimes comprise a housing 11 formedin two parts, a hollow generally rectangular shaped cover or casing 12and a flat back plate (not shown) which is a close fit in the open sideof the cover 12. The longitudinal sides 14 of the cover are slightlybowed outwardly to provide a pleasing appearance. The top or front ofthe cover is formed with five bands of narrow grooves 15 separated byraised fiat strips 16 and the ends 17 of the casing are fiat but areprovided with outwardly-extending flanges 18 at their lower edges toenable the housing 11 to be fixed to a wall or other surface. The cover12 is moulded in plastic material.

The tone bars 19 and 29 and the striker assembly 21 are mounted withinthe casing 12 on a mounting unit 22. The mounting unit 22 is formed froma sheet of ferromagnetic material and comprising a generally square cen-Patented May 4-, 1365 tral portion 23 and four L.-shaped arm portions24. When the sheet is flat the arm portions 24 extend outwardly from twoopposite sides 25 of the central portion 23 of the sheet at the cornersthereof so that one limb 26 of each arm 24 extends parallel to the othersides 27 of the sheet and the other or free limb 28 of each arm 24extends parallel to the first said sides 25 of the central portion 23 ofthe sheet. The free limbs 28 are each formed with a constricted portion29 adjacent their free ends. The arms 24 are pressed out of the plane ofthe sheet to lie in parallel planes perpendicular thereto and are bracedby triangular sectioned portions 36 of the arms 24 which are deformedout of the plane of the arms 24 to give the arms a degree of rigidity.Four frusto-conical shaped depressions 31 are formed in the centralportion 23 of the sheet and seat on small stubs (not shown) provided onthe inner face 32 of the cover 12. The sheet 22 is secured to the cover12 by two screws 33 threaded into two diametrically opposed stubs.

A semi-circular ended elongated arm 34 outstands from one of the sides27 of the central portion 23 of the plate 22 centrally in the lengththereof and is deformed upwardly out of the plane of the sheet 22 to liein a plane at right angles thereto. A similar arm 35 is pressed out ofthe central portion 23 of the sheet to lie in a plane parallel to andspaced from the first arm 34. The first arm 34 has a circular aperture36 through it and the second arm has an open-ended slot 37 formed in it.The slot 37 extends axially into the arm 35 from the end thereof anddecreases in width intermediate its length to form a part-circularseating 38 of greater than 180 angular extent. The sides of the slotabove the seating 38 converge slightly towards each other and the sides39 of the slot below the seating 38 are parallel and closely adjacentone another. The two arms 34 and 35 provide a holder for the operatingcoil 41 of the chimes. The coil 41 is energised through two screwconnectors 42 housed in one of the end flanges 18 of the cover 12 andwhich are connected to the ends of the coil 41 by wires 43.

The coil 41 closely encircles a brass tube 44 which is slightly longerthan the coil 41. The external diameter of the tube 44 is such that itis a fit in the aperture 36 in the arm 34 and in the portion of the slot37 in the other arm 35 above the seating 38. To mount the coil 41 in itsmounting unit 22, the coil 41 is held above the unit 22 so that thebrass tube 44 overlies the aperture 36 and the slot 37. The coil 41 isthen moved downwardly into the space between the arms 34 and 35 so thatone end 45 of the tube 44 slides against the inner surface of the arm 34and the end face of the coil 46 adjacent the other end 47 of the tube 44slides against the inner surface of the other arm 35. The end 47 of thetube 44 passes along the slot 37 in the arm 35. The axial length of thecoil 41 is substantially equal to the normal spacing of the arms 34- and35 and consequently the two arms 34 and 35 are slightly forced apartwhen the coil 41 and core 44 are passed into the space between them. Thecoil 41 and core 44 are pushed into the holder until the end 45 of thetube 44 registers with the aperture 36. The arms 34 and 35 are then nolonger forced apart and come in towards each other under their ownresilience. The end 45 of the tube 44 then passes through the aperture36. When the coil 41 is inserted into the mounting unit 22 there is aclick as the end 45 of the tube 44 engages in the aperture 36.

In this example, the tone bars 19 and 29 comprise two rectangularsectioned strips of metal and are cadmium plated. Each strip is about 5/2 inches long, 1 inch in width and is provided with two apertures 48(only one shown) spaced respectively about 1 /8 inches and 1% inchesfrom the ends thereof. The bars 19 and 20 are mounted between theflanges 49 of flanged rubber bushes 51 threaded on to the constrictedportions 29 of the arms 24. The axial length of the bush 51 between theflanges i 49 is greater than the thickness of the bars 19 and 2t) andthe diameter of the bar apertures 48 are greater than the externaldiameter of the bushes 51' between the flanges 4h.

. Consequently, the tone bars can move relative to the The bars 19, 2t!are set into vibration by a striker unit 21. This unit 21 comprises athick-walled soft iron plunger 52 which is a sliding fit in the core 44of the coil 41. Two short plastic (cg. nylon) striker rods 53 and 54 areinserted in blind axial bores in the ends of the plunger 52 and projectfrom each end thereof. plunger 52 is encircled by a light compressionspring 55 which acts between the arm 35 and a spring washer 56 engagingthe striker rod- 54 adjacent one end thereof. In its extended condition,the spring 55 maintains that end of the striker rod 54 slightly spacedfrom the adjacent tone bar 20.

Four similar rectangular apertures 57 are formed through the sides ofthe casing .12, two in each side, each aperture being aligned withan endof a tone bar 19 or 20. Each aperture 57 extends for substantially thewhole Width of the tone bar 19 and and extends along the length of thetone bar from an end thereof to adjacent a bush 51 on which it ismounted. In this example, the apertures taper in Width from about A; ofan inch to about of an inch adjacent the back 32 of the cover 12 and areabout of an inch long.

When the coil 41 is energised, the plunger 52 is drawn rapidly into thecoil 41 causing an end of the nylon striker rod 53' to strike againstone of the tone bars 19. That bar 19 is therefore caused to vibrate,nodes occurring at the positions at which the bar 19 is mounted. Whenthe coil 41 is de-energised, the plunger 52 is moved rapidly in theopposite direction by its encircling spring .55 and strikes against theother tone bar 29. That bar 2%) is therefore also caused to vibrate,again nodes occur at the positions at which the bar 20 is mounted. Thetwo tone bars 19 and 20 are struck approximately centrally and sub.-stantially perpendicular to their length. Consequently the principal ormajor vibrations set up in each tone bar occur in a plane perpendicularto the longitudinal axial plane of the tone bar. The plane in which themajor vibra- The tions, occur is therefore substantially perpendicularto the appropriate aperture 57 and consequently the major vibrationstake place in a direction towards and away from the aperture. Themounting unit completes the magnetic circuit of the coil and plungermechanism.

I'E'Wlll be noted that-the door chime does nothave any separateresonating chambers or tubes. The function of these resonating chambersor tubes is fulfilled by the easing 12 which is tuned as near aspossible to the frequencies of the two tone bars 19 and 20 to give themaximum dura- 60 tion of resonance of these bars. While this must, ofcourse, be a compromise, I have found that the duration 4 i of resonanceis only slightly less than that achieved with separate resonatingchambers or tubes.

It will also be appreciated that the assembly of the various parts onthe mounting unit 22 can be readily and speedily effected. Similarly themounting unit 22 can be readily and speedily attached to the cover 12 tocomplete assembly of the door chime.

The invention is not restricted to the details of the foregoing example.For instance, any number of apertures may be formed through thecover ofthe chime.

I claim:

1. For an electrical signalling device the combination of:

(a). a striker mechanism,

(b) a tone barhaving'sup'port openings therethrough,

(c) a mounting having a base part,

(d) a pair of spaced resilient arms'upstandingfrom the base part andreleasably and resiliently gripping the striker mechanism, I

(e) a further pair of resilient arms upstanding from the base part andhaving at their free endsparts which extend in a direction parallel tothe base part, the'said parts having constrictions. along their length,and

(f) resilient grommets surrounding the said constrictions and passingthrough'the support. apertures. to support the tone bar on the saidfurther arms.

2. An electrical signalling device, comprising:

(a) a ferro-magnetic support member,

(b) a pair of tone oars,

(c) a striker mechanism including a plunger armature and a solenoid coilWound onto anon-magnetic tube,

(d) three pairs of arms pressed out of and integral with the supportmember, two pairs of said arms being located at opposite sides of thesupport member and each releasably supporting one of said tone barsintermediate the opposite ends thereof, and the third pair of saidarmsresiliently and releasably gripping said coil at a position betweensaiditone bars, there being a low reluctance path between saidv thirdpair of arms, and

(e) a casing comprising a flat cover part and four surrounding sideparts projecting therefrom, the support member being secured to the flatcover part within the side parts and with the tone bars and strikermechanism within the said side parts, said casing having sound aperturesopposite the antinodes of maximum vibration at the ends of the tonebars.

References Cited by the Examiner V UNITED STATES PATENTS 1,307,467

NEIL C. READ, Primary Examiner. RUDOLPH V. ROLINEC, Examiner.

2. AN ELECTRICAL SIGNALLING DEVICE, COMPRISING: (A) A FERRO-MAGNETICSUPPORT MEMBER, (B) A PAIR OF TONE BARS, (A) A SRIKER MECHANISMINCLUDING A PLUNGER ARMATURE AND A SOLENOID COIL WOUND ONTO ANON-MAGNETIC TUBE,